Active seat suspension systems including systems with non-back-drivable actuators

ABSTRACT

Embodiments related to active vibration isolation systems for a vehicle seat, as well as their methods of use, are disclosed. In some embodiments, an active suspension system may be configured to support a seat above a floor of a vehicle. The active suspension system may include two or more actuators that may be operated cooperatively to control both the roll and heave of the vehicle seat. In some instances, these actuators may also be non-back-drivable actuators. Additionally, in some embodiments, an active suspension system may include one or more torsion springs that apply torques in parallel with associated actuators of the active suspension system to support at least a portion of the loads applied to the active suspension system during operation.

FIELD

This disclosure relates to an active seat suspension systems that mayinclude non-back-drivable actuators in some embodiments.

BACKGROUND

Active vibration isolation systems can be used with vehicle seats tocounteract rolling and jarring motions of vehicle. Many such systems aretoo large to be used in passenger cars.

SUMMARY

In one embodiment, an active suspension system may be configured tosupport a vehicle seat relative to a floor of the vehicle. The activesuspension system may also include a first non-back-drivable actuatorand a second non-back-drivable actuator. The first non-back-drivableactuator and the second non-back-drivable actuator may be configured tobe operated cooperatively to control both roll and heave of the vehicleseat.

In another embodiment, a method of operating an active suspension systemto support a vehicle seat relative to a floor of the vehicle mayinclude: cooperatively operating a first non-back-drivable actuator anda second non-back-drivable actuator to control both roll and heave ofthe vehicle seat.

In yet another embodiment, an active suspension system may be configuredto support a vehicle seat relative to a floor of the vehicle. The activesuspension system may also include a first actuator and a first rockerarm that is operatively connected to the first actuator. The firstrocker arm may be constructed to be connected to the vehicle seat, andthe first actuator may be constructed to apply a torque to the firstrocker arm. The active suspension system may also include a firsttorsion spring that applies a torque to the first rocker arm.

In still another embodiment, a method of operating an active suspensionsystem to support a vehicle seat relative to a floor of the vehicle mayinclude: applying a first torque to a first rocker arm connected to thevehicle seat with a first actuator; and applying a second torque to thefirst rocker arm in parallel with the first torque.

It should be appreciated that the foregoing concepts, and additionalconcepts discussed below, may be arranged in any suitable combination,as the present disclosure is not limited in this respect. Further, otheradvantages and novel features of the present disclosure will becomeapparent from the following detailed description of various non-limitingembodiments when considered in conjunction with the accompanyingfigures.

In cases where the present specification and a document incorporated byreference include conflicting and/or inconsistent disclosure, thepresent specification shall control. If two or more documentsincorporated by reference include conflicting and/or inconsistentdisclosure with respect to each other, then the document having thelater effective date shall control.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures may be represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 is schematic diagram of an active vibration isolation system usedfor a seat of a vehicle.

FIG. 2 is a functional block diagram of one example of the system ofFIG. 1.

FIG. 3 is a more detailed functional block diagram of another example ofthe system of FIG. 1.

FIG. 4 is a top perspective view of an active suspension system for theactive vibration isolation system.

FIG. 5 is a top view of the active suspension system of FIG. 4.

FIG. 6 is a partial view, showing the actuators of the active suspensionsystem of FIG. 4.

FIG. 7 is a detailed view of one actuator of the active suspensionsystem of FIG. 4.

FIG. 8 is a top perspective view of a seat support/air spring assemblyfor an active vibration isolation system.

FIG. 9 shows the seat support/air spring assembly of FIG. 8 mounted tothe active suspension system of FIG. 4.

FIG. 10 is a bottom perspective view of the seat support/air springassembly of FIG. 8 mounted to a seat.

FIG. 11 is a perspective view of a demonstration system for the activevibration isolation system.

FIG. 12 is a top perspective view of another example of an activesuspension system for the active vibration isolation system.

FIG. 13 is a top perspective view of a seat support/air spring assemblyfor the active suspension system of FIG. 12.

FIG. 14 is a schematic perspective view of another embodiment of anactive suspension system for a vehicle seat.

FIG. 15 is a schematic side view of another embodiment of an activesuspension system for a vehicle seat.

FIG. 16 is a schematic side view of another embodiment of an activesuspension system for a vehicle seat.

FIG. 17 is a schematic side view of another embodiment of an activesuspension system for a vehicle seat.

FIG. 18 is a schematic side view of another embodiment of an activesuspension system for a vehicle seat.

FIG. 19 is a schematic top view of another embodiment of an activesuspension system for a vehicle seat.

FIG. 20 is a schematic side view of an active suspension systemincluding a variable torsion spring.

DETAILED DESCRIPTION

The Inventors have recognized that prior systems used for mitigatingmotion of a vehicle occupant have been bulky, complex, and difficult tointegrate within the limited space available in passenger vehicles.Additionally, the control of such systems has tended to be rathercomplex due to the complicated mechanisms and separate systems used forcontrolling motion of a vehicle occupant. Accordingly, the Inventorshave recognized a need for active vibration isolation systems to helpmitigate the motion applied to vehicle occupants in various instances.In some applications, these systems may provide relatively reducedcomplexity and smaller form factors while providing desired forcegeneration amounts and desired response times. However, embodiments inwhich other benefits and/or a subset of the above noted benefits arerealized are also possible.

In view of the above, the Inventors have recognized the benefitsassociated with an active vibration isolation system that includes anactive suspension system with two actuators that are operativelyconnected to a vehicle seat. Specifically, in some embodiments, thefirst and second actuators may be constructed and arranged such thatthey may be actuated in a cooperative manner to control at least one, orboth, the roll and heave of an associated vehicle seat at any giventime. Thus, the active suspension system may be used to compensate formotion of the vehicle caused by road inputs, driver inputs, and/or othermulti-directional accelerations that may be applied to the vehicle. Ofcourse, it should be understood that while only first and secondactuators are noted above, embodiments in which more than two actuatorsare included in an active suspension system of a vehicle seat are alsocontemplated.

In one embodiment of an active suspension system, first and secondactuators may be operatively coupled to two or more rotatable rockerarms connected to opposing sides or portions of a vehicle seat. Theactuators may be actuated to rotate the rocker arms. Depending on thecombined motion provided by operation of the actuators, this cooperativerotation of the rocker arms may either raise, lower, rotate, and/orprovide a combination of the above motions for the associated vehicleseat. Specific embodiments and methods of implementing such a system aredescribed in further detail below.

In addition to the above, in some embodiments, an active suspensionsystem of a vehicle seat may include one or more, and in at least oneembodiment, at least two non-back-drivable actuators to control rolland/or heave of an associated vehicle seat. In some instances, all ofthe actuators included in the active suspension system may benon-back-drivable actuators. In such an embodiment, thenon-back-drivable actuators may be operated cooperatively to controlone, or both, of roll and heave of the vehicle seat.

The Inventors have recognized multiple benefits associated with the useof non-back-drivable actuators. For example, in one embodiment, anon-back-drivable actuator may support at least a portion, or theentire, weight of a seat and an occupant of the seat without thecontinued application of torque that might be required from aback-drivable actuator. This may lead to reduced power consumption bythe system. Additionally, in some embodiments, a non-back-drivableactuator may be used without a spring, such as an air spring for exampleand its associated air pump, which may result in a less complicated,less costly, and more reliable design. Due to the elimination of bulkyair springs in some embodiments, non-back-drivable actuators may also beused to provide a more compact design that may be more easilyaccommodated in the limited space located beneath typical vehicle seats.In some embodiments, non-back-drivable actuators, such as worm drives,may also exhibit increased ranges of motion for the overall system ascompared to suspension systems including linear actuators. These, andother benefits, are discussed in more detail below in regards to thevarious embodiments.

As used herein, the term “heave” may refer to motion of a seat in agenerally vertical direction relative to the vehicle's frame ofreference, which in some embodiments herein may be referred to asmovement along a Z-axis of a seat and/or vehicle. For example, when avehicle is stationary and located on level ground, a vertically orientedaxis may extend upwards in a direction that is perpendicular to thelevel ground. Further, in some embodiments, this vertically orientedaxis may also be approximately perpendicular to a direction in which anunderlying surface of the vehicle interior generally extends even thougha floor of a vehicle interior typically is not flat. In either case, itshould be understood that even when a vehicle is no longer located onlevel ground, terms such as heave, vertical movement, movement along aZ-axis, and/or other similar terms may refer to movement of the seat ina direction that is parallel to this vertical axis which may remainapproximately vertical relative to the vehicle's frame of reference.Thus, a vertical axis of a vehicle and/or seat, as well as theassociated types of movement noted above, may be understood to be avertical axis fixed relative to a reference frame of the vehicle, not aglobal reference frame.

As used herein, the term “roll” may refer to the rotational motion of aseat about an axis that is parallel to a generally longitudinal axis ofthe vehicle passing from a front to a rear of the vehicle. In someembodiments, this may be referred to as roll of a seat or rotation ofthe seat about an X-axis of the seat, seat base or vehicle. For example,when a vehicle is, not loaded, stationary and located on level ground, alongitudinal axis of the vehicle may pass from a front of the vehicle toa rear of the vehicle in a direction that is generally parallel to theground. The seat may then rotate, or roll, about an axis that extends ina direction that is parallel to this longitudinal axis of the vehicle.Further, even when the vehicle is not located on level ground, thislongitudinal axis still passes from a front of the vehicle to a rear ofthe vehicle relative to the vehicle's frame of reference regardless ofthe vehicle's global orientation.

For the sake of clarity, the embodiments described herein are primarilydirect to rotation of a vehicle seat to change a roll of the vehicleseat, i.e. rotation of the seat about an axis parallel to a longitudinalaxis of the vehicle. However, embodiments in which the disclosed activesuspension systems are used to control rotation of the vehicle seatabout a different axis that is generally parallel and/or perpendicularto an underlying surface of a vehicle interior are also contemplated.For example, the disclosed active suspension systems may also be used tocontrol a pitch of a vehicle seat as well as rotation about any otherappropriate axis as the disclosure is not limited in this fashion.

Turning now to the figures, several non-limiting embodiments aredescribed in further detail. While specific combinations of variousfeatures, components, and systems are described relative to the figures,should be understood that the current disclosure is not limited to onlythe depicted embodiments. Instead, combinations of the various features,components, and systems are contemplated as the disclosure is notlimited in this fashion.

An active vibration isolation system may be used to maintain the heightof a seat base constant in space as the vehicle moves up and down androlls, and also can be used to maintain the user's torso or head in asubstantially constant lateral and/or vertical position as the vehiclemoves up and down and rolls. A substantially constant position maycorrespond to maintaining a lateral and or vertical position withinabout 3 inches, 2 inches, 1 inches, 0.5 inches, and/or any otherappropriate distance relative to an initial position of a user's torsoor head. These motions can be accomplished, within system limits,independently of the user's weight. Further, the system open-looptransfer function is largely independent of the weight carried by theseat, leading to a simple and robust controller design. Of course, othermethods of operating an active vibration isolation system and associatedactive suspension system to control motion of a seat and a user are alsocontemplated.

In one embodiment, an active vibration isolation system 10, FIG. 1, isadapted to control motions of vehicle seat 12 (via seat base 14 thatsupports seat 12) relative to vehicle floor 16. Active suspension system20 supports seat base 14 above floor 16. Active suspension system 20 isadapted to move seat base 14 up and down in the direction of verticalaxis Z. Active suspension system 20 is also adapted to rotate seat base14 in both directions (left and right) about horizontal, forward-facingaxis X.

Active vibration isolation system 10 can in one non-limiting example beoperated with the aim of maintaining the lateral (side-to-side) positionof the upper torso/head of a person sitting in seat 12 while the vehicleundergoes rotations about a forward vehicle axis that is parallel to orcoincident with axis X (such rotations also known as vehicle “roll”).This user lateral position control is further described in US PatentApplication Publication 2014/0316661, entitled “Seat System for aVehicle,” the disclosure of which is incorporated herein by reference.Accordingly, user lateral position control will not be further describedherein. System 10 can be operated in other manners (with other controlalgorithms). For example, system 10 can be operated to move the occupant(via the seat), or to move the seat per se, in other prescribed(pre-calculated) manners.

Active suspension system 20 may also adapted to translate seat base 14up and down parallel to the vertical (Z) axis. Active vibrationisolation system 10 can in one non-limiting example be operated with theaim of maintaining seat base 14 (and thus seat 12 and a person sittingin seat 12) at a constant height in space while vehicle floor 16 movesup and down as the vehicle travels over a surface. As described aboverelative to lateral positioning, seat translations can be designed toachieve other motions or other goals.

A system 10 may also include a sensor 30 (which may comprise one or morephysical sensing devices) mounted to the vehicle (in this non-limitingexample, mounted to vehicle floor 16). Sensor 30 may be an absolutesensor that, alone or in conjunction with operations performed bycontroller 22, senses vehicle rotational position changes about axis X(or, an axis parallel to axis X), and vehicle height position changesalong (or parallel to) axis Z. System 10 may also include a seatposition sensor 32 (which may comprise one or more physical sensingdevices) that may preferably be a relative sensor that, alone or inconjunction with controller 22, determines the seat roll positionrelative to the vehicle about axis X (or, an axis parallel to axis X),and the seat translational position relative to the vehicle along (orparallel to) axis Z. System 10 may also include optional seat neutralposition sensor 34 (which may comprise one or more physical sensingdevices) that may preferably be a relative sensor that, alone or inconjunction with controller 22, determines “neutral” seat Z axis androll positions. Neutral position sensor 34 can be enabled to change itsoutput state at the mid positions of the seat in roll and Z.Accordingly, it can also provide knowledge of whether the seat is aboveor below the mid height position, and whether the seat is to the left orright of the seat horizontal (i.e., roll neutral) position. Neutralposition sensor 34 can also be used to re-calibrate system 10 each timethe seat moves through either of these neutral positions, as is furtherexplained below. In cases where system 10 includes sensors 30 and 32 butnot sensor 34, sensor 32 could be an absolute calibrated sensor so thatit can be used to report the actual seat position, which also providesinformation concerning the seat position relative to the height and rollneutral positions.

In the depicted embodiment, a controller 22 may receive the outputs ofsensors 30 and 32 (and the output of sensor 34 when sensor 34 is used)and in response provide appropriate control signals to active suspensionsystem 20 so as to achieve the results of the particular active seatposition control algorithms that are designed into system 10.Non-limiting examples of the goals of such algorithms are describedabove. One specific non-limiting example is to maintain (as best aspossible) the user's head/torso lateral position and the user's Zposition as the vehicle undergoes rotations about axis X andtranslations along axis Z. Though other control methods are alsocontemplated as the disclosure is not limited to any particular controlstrategy. Power for the controller and the active suspension system istypically provided via the vehicle electrical system, commonly at 12V,with appropriate conditioning and the like to meet the requirements ofsystem 10.

One embodiment of a functional block diagram of an active vibrationisolation system 50 is depicted in FIG. 2. System 50 differs from system10, FIG. 1, in that active suspension system 20 a in this case includesseat position servo 40 and force bias device 46. A force bias device isa passive suspension device such as a spring, but with an adjustablespring force. One goal of the force bias device is to support the seatand user in a nominal neutral position while the vehicle is at rest, sothat the active suspension does not need to be engaged at all times,which saves vehicle power. This also saves vehicle power when the activesuspension is operated, as much of the weight is supported by the forcebias device so that the actuators do not need to produce as much force.Several examples of force bias devices for active vehicle seat controlare further described in U.S. Pat. No. 8,095,268, issued on Jan. 10,2012, the disclosure of which is incorporated herein by reference. Aspecific embodiment of a force bias device including torsion springs isdetailed further below. Seat position servo 40 may be a high bandwidthposition servo that is adapted to control the roll and Z axis positionsof the seat. Servo 40 is able to create (within limits) forces tomaintain the desired seat positions. In this example, position servo 40may include two actuators; a first actuator (42) and second actuator(44). Actuators 42 and 44 can be of any design and construction that iscapable of moving the seat in the desired directions. In thisnon-limiting example the actuators are back-drivable linear actuators.However, embodiments in which non-back-drivable and/or rotary actuatorsmay be used are also contemplated.

A more detailed block diagram of one embodiment of an active vibrationisolation system 60 is shown in FIG. 3. Actuators 42 a and 44 a in thisnon-limiting example each comprise a rotary motor (70, 80) that drives alinear actuator (72, 82) which in turn moves a rocker arm (74, 84) thatis directly or indirectly mechanically coupled to seat base 62. The useof two separately controlled actuators allows control of both thevertical and roll positions of the seat base, and thus the seat and theperson sitting in the seat. This is further described below.

Position encoders 76 and 86 may be relative sensors that measure therotational positions of motors 70 and 80, respectively. Controller 22may be programmed to calculate from the encoder data the seat positionrelative to the vehicle in both Z and roll. Neutral position sensors 78and 88 (when used) may also preferably be one-bit Hall sensors at topdead center (neutral position) of each of the rocker arms. Sensors 78and 88 accordingly may produce output signals each time the respectiverocker arm moves through the neutral position; these data can be used tohelp determine which direction(s) to move the seat, and also tocalibrate the system on the fly so as to maintain the accuracy of theseat position calculations in both Z and roll. FIG. 3 also illustratesthe use of an air spring 96 as a force bias device. The air spring mayalso use a pressure source and a valve (not shown). An alternative wouldbe to use one or more torsion springs, as further described below, orother springs with adjustable spring forces. Additionally, more than oneforce bias device could be used, and more than one type could be used(e.g., an air spring and one or more torsion springs).

Controller 22 may receive signals from a vehicle roll sensor (which maybe a rate gyroscope) 90, vehicle Z axis accelerometer 92, positionencoders 76 and 86, and/or neutral position sensors 78 and 88. The gyroinput may be integrated, and the accelerometer input may be doubleintegrated, to obtain the rotational and vertical displacement signals.Controller 22 may output in response to all of its inputs, controlsignals for rotary motors 70 and 80, and control signals to the valvefor air spring 96. These control signals are designed to achieve userposition control as prescribed by the appropriate control algorithm. Inone example control algorithm described above, the lateral and/orvertical positions of a user may be maintained. To accomplish this, seatbase 62 may be moved so as to, in limit, maintain its z position inspace as the vehicle moves up and down and rolls, and seat base 62 isalso moved so as to, in limit, maintain the user's torso or head in aconstant lateral position as the vehicle moves up and down and rollsabout the forward vehicle axis parallel to or coincident with the Xaxis. Different seat base motions could be commanded so as to accomplishother control algorithms.

Within limits, system 60 may accomplish these above noted motionsindependent of the user's weight. In some embodiments, system 60 may beable to maintain the static seat height independently of the user'sweight because the spring (e.g., the air spring or the torsion barspring) is able to provide a spring force to match the user's weight.Also, the operation of system 60 is largely independent of the springrate and the natural frequency of the user on the seat. In contrast,prior systems such as that described in US Patent ApplicationPublication No. 2006/0261647 attempt to preserve a natural frequency ofthe user on the seat, regardless of the user's weight, by using aprogressive spring rate spring. The heavier the user the further thespring is compressed in order to reach a section of the spring with agreater spring rate. Accordingly, the static compression of the springis dependent on the user's weight, and so the static seat height is alsodependent on user weight.

The operation of controller 22 may also be largely independent of auser's weight. For example, system 60 may use position sources ratherthan force sources for example, and without wishing to be bound bytheory, with a force source the user's weight is a large contributor tothe system dynamics: as the actuator motion ratio increases, the movingmass of the actuator itself becomes of greater significance indetermining the system dynamics while the mass of the user becomes oflesser significance to the system dynamics. In contrast, in thedisclosed systems where position sources may be used in someembodiments, the motion of the actuator may be largely independent ofthe payload (either the weight of the user or the moving mass of theactuator) and only commands to the controller. This may provide asimpler, more robust controller design.

System 60 may also be adapted to manage the end of range of travelregions so as to minimize jarring motions that might occur when thevehicle experiences excursions that would result in greater roll or zaxis motion than the system is able to accomplish. For example, if thevehicle is driven over a deep pothole at relatively high speed thevehicle floor will move down quickly and substantially. System 60 willextend the seat suspension upward, with the goal of maintaining the seatat a constant height in space. However, the upward travel is inherentlylimited by the construction of the seat suspension. The same applies fordownward travel, and the left and right roll limits. In order to softenany jarring that might occur if the seat is moved quickly to its end oftravel range (in the Z and/or X axes), controller 22 may be adapted to“harden” or “stiffen” the seat suspension as end of travel range isapproached. Such stiffening could be progressive, so as to prevent theseat from ever reaching the end of travel range. Or, the system couldallow the end of travel range to be met, but in a manner that slows theseat velocity as the end of range is approached. Since system 60 uses aposition servo rather than a force source, such stiffening could beaccomplished by reducing the amount of seat translation per vehicledisplacement (as determined from the accelerometer signals).

Details of one non-limiting example of active suspension system 20 b forthe active vibration isolation system are shown in FIGS. 4-7. Actuators42 a and 44 a are held in place by box-shaped support frame 91 thatcomprises opposing front 97 and rear 98 portions as well as opposingsides 99 and 103 that extend between the front and rear portions of theframe. Actuators 42 a and 44 a are linear actuators. Linear actuatorscould be accomplished in any desired manner, such as with linear motors,or, as described below, with rotary motors that drive rotary to linearconverters. Rotary to linear converters are known in the art, and maycomprise, for example, ball screw assemblies, lead screws or wormdrives. Additionally, as detailed further below, in some embodiments,the actuators may be non-back-drivable actuators.

Actuator 42 a may comprise rotary motor 70 with its output coupled toball screw assembly 72 a that converts input rotary motion to outputlinear motion. The coupling of the motor to the ball screw assembly (notshown) can be accomplished using a cogged belt or v-belt or chain, orany other such coupling as would be known in the art such as a geartrain or direct coupling; this coupling may be protected by guard 85.Ball screw assembly 72 a output shaft 113 is coupled to rocker arm 74 a.The other end of the ball screw assembly may be fixed to frame 91.Rocker arm 74 a comprises link 100 (with rotational axis 101) that isfixed to bar 102 (with rotational axis 180). Links 104 and 106 are fixedto and extend from bar 102, and have distal ends 105 and 107. Asexplained below, the seat is (indirectly) coupled to ends 105 and 107.Rocker arm 74 a translates linear input motion to rotational outputmotion. Actuator 44 a may comprise rotary motor 80 with its outputcoupled to ball screw assembly 82 a that converts input rotary motion tooutput linear motion. The coupling of the motor to the ball screwassembly can be accomplished using a cogged belt or v-belt or chain, orany other such coupling as would be known in the art such as a geartrain or direct coupling; this coupling is protected by guard 83. Ballscrew assembly 82 a output shaft 109 is coupled to rocker arm 84 a. Theother end of the ball screw assembly is fixed to frame 91. Rocker arm 84a comprises link 110 (with rotational axis 111) that is fixed to bar 112(with rotational axis 182). Links 114 and 116 are fixed to and extendfrom bar 112. Pivoting links 118 and 120 are pivotally coupled to theends of links 114 and 116, and are adapted to rotate about axis 130. Asexplained below, the seat is (indirectly) coupled to ends 119 and 121 oflinks 118 and 120, along axis 123. Rocker arm 84 a translates linearinput motion to rotational output motion.

While rocker arms corresponding to a bar with radially extending linksattached thereto has been depicted in the figures, it should beunderstood that a rocker arm may correspond to any appropriate rotatablestructure that is rotatable about a rotational axis of the structure andthat includes one or more portions that extend radially outward from therotational axis and that may be operatively connected to a base of acorresponding seat. Accordingly, rotation of the rocker arm may betranslated into vertical displacement of the portion of the seat baseconnected to the radially extending portion, or portions, of the rockerarm.

One embodiment of a seat support/air spring assembly 150 is shown byitself in FIG. 8, and is shown mounted to active suspension system 20 bin FIG. 9. Assembly 150 comprises rigid mechanical seat support 160 thatitself comprises central member 162 and seat supporting cross members164 and 166. Air spring 170 is coupled to the bottom of member 162, andis supported on the vehicle floor (not shown) by load spreader 172. Asshown in FIG. 9, member 166 is coupled to link ends 105 and 107 suchthat when rocker arm 74 a is rotated, member 166 moves along arc 190.Member 164 is coupled to link ends 119 and 121. When rocker arm 84 a isrotated, links 116 and 118 are moved along arc 192. Link ends 119 and121 are able to rotate about arc 194. Pivoting links 118 and 120 areneeded to translate the arcuate motions of the ends of the rocker arm tovertical motion of the seat.

FIG. 10 shows an embodiment of a seat support/air spring assembly 150mounted to the bottom of seat S. Since members 164 and 166 can beindependently moved up or down by active suspension system 20 b, theseat is able to pivot both ways about axis X and translate up and downalong axis Z (FIG. 1). For example, when both actuators are extended theseat moves up, and when one is extended and one retracted the seatrolls. If only one is extended the seat motion is partiallytranslational and partially a roll. Thus, the active vibration isolationsystem is able to move the seat so as to maintain the user's head/torsoin a fixed translational (side-to-side) position and maintain the seat(and thus the user's head) at a constant height in space (both, tolimits) while the vehicle rolls and translates up and down, though othercontrol schemes are also contemplated as noted previously.

In one embodiment the force bias device is accomplished partially orcompletely with one or more torsion springs. A torsion spring can beaccomplished with a torsion bar, which can be mounted within bar 102and/or bar 112. Though external mountings of a torsion bar and/ortorsion helical spring may also be used. Such torsion bars would act onthe seat through the ends of the rocker arms. The force provided by atorsion spring can be adjusted by changing the degree of twist impartedto the spring. A specific embodiment of such a device is detailedfurther below.

When rotary motors and ball screw assemblies are used in combination aslinear actuators, the motors can be small 12V electric motors with highmotion ratio such that a small amount of power can produce a smallamount of motor output torque, but result in a high force output via theball screw assembly. The ball screw assemblies can be effectivelynon-back-drivable devices so that the actuators hold their positionswell. One result of this arrangement, and the horizontal orientations ofthe motors and ball screw assemblies, is that the active suspensionsystem (which is located between the seat and the vehicle floor) has alow profile—perhaps in the range of about 8-10 cm. This lends itself touse of the active vibration isolation system in all kinds of vehicles,including vehicles with little headroom such as passenger cars.

FIG. 11 is a perspective view of a demonstration system 210 forincluding one embodiment of an active vibration isolation system. Thedemonstration system is constructed and arranged to demonstrate themotions that can be accomplished by an active vibration isolationsystem, such as the systems described above. System 210 is in one usesituation able to easily replicate vehicle roll, and can demonstrate theresponses to roll of active suspension system 20 b. Vehicle roll isreplicated by the use of rocker platform 200 that is coupled belowactive suspension system 20 b, such that platform 200 rests on thefloor. Rocker members 202 and 204 may have curved bottom surfaces 206and 208. Cross-members 205 and 207 may help to maintain rigidity. Thisconstruction of rocker platform 200 allows the seat S to move side toside, like a sideways rocking chair. Movement can be accomplished in adesired manner, for example by pushing on one side of seat S. If theactive suspension system is engaged, it may be operated to cause motionsof the seat aimed to maintain the lateral position of the user's head ortorso as the seat is pushed. In an alternative arrangement the activesuspension system can be turned on after the rocking motion has begun,so the user can feel the rocking motion (roll) and then the system'sresponse to the roll. In yet another alternative use situation, activesuspension system 20 b can be commanded to cause motions of the seatthat initiate the side-to-side rocking motion (a “self-actuated mode”).The self-actuated mode can be used as desired, for example to drawattention to the demonstration system in a vehicle showroom or the floorof a trade show. System 210 can be accomplished simply by providingrocker platform 200 and programming the controller to achieve thedesired motions. Appropriate power supplies (e.g., 120V to 12V adapters)may also be needed.

FIG. 12 is a perspective view of another example of one embodiment of anactive suspension system 20 c. System 20 c differs from activesuspension system 20 b, FIG. 4, in that active suspension system 20 cmay include a passive isolation stage 300. In some implementations, whenthe disturbances in the Z and roll directions are mitigated, the mostsignificant remaining component of disturbance is in the fore-aft orX-direction. The passive isolation stage 300 included in the system 20 cmay serve to mitigate these fore-aft vibrations. The seat S (FIG. 10)mounted to the active suspension system 20 c may move along the fore-aftdirection as described below. Each side of the passive isolation stage300 (only a single side is visible in FIG. 12) includes a shaft 302,mounted between the links 104, 106 of rocker arm 74 a and between thelinks 114 and 116 of rocker arm 84 a (FIGS. 4 and 6).

As also shown in the depicted embodiment, two linear sleeve bushings 304a, 304 b may be disposed along the shaft 302 and enable the isolationstage 300 (and the seat S connected thereto) to move along the axis ofthe shaft 302 in the fore-aft direction. Springs 306 a, 306 b aremounted between the cross members 364, 366 of the rigid mechanical seatsupport 360 (described in more detail with respect FIG. 13 below) andspring fasteners 308 a, 308 b affixed to the shaft 302. Springs 306 aand 306 b provides restorative force to bias the seat S toward thecenter of the range of travel in the fore-act direction when not beingdisturbed. When the vehicle undergoes fore-aft motions, the linearsleeve bushings 304 a and 304 b and the springs 306 a and 306 b absorbthe relative motion and allow the seat S to remain largely stationarywhile the vehicle oscillates fore-aft.

FIG. 13 is a top perspective view of an embodiment of a seat support/airspring assembly 350 for the active suspension system of FIG. 12. Thesupport/air spring assembly 350 is comparable to the seat support airspring assembly 150 (FIGS. 8, 9) with differences to be described below.The assembly 350 is shown mounted to the active suspension system 20 cin FIG. 12, and shown by itself in FIG. 13. Assembly 350 includes therigid mechanical seat support 360 that itself comprises central member362 and seat supporting cross members 364 and 366. Air spring 370 iscoupled to the bottom of member 362 and is supported on the vehiclefloor (not shown) by pivot assembly 372 to allow the connected end ofthe air spring 370 to rotate about transverse axis 378 as the assembly350 (and connected seat S) moves in the fore-aft direction. The pivotassembly 372 includes an upper portion 374 connected to the air spring370 and a lower portion 376 supported by the vehicle floor (not shown)which allows rotational motion about the axis 378, which extendsorthogonally to the fore-aft or X-direction. The air spring 370 isthereby supported by and rotatably connected to the vehicle floor, asthe assembly 350 (and connected seat S) moves in the fore-aft direction.

In some exemplary embodiments, a lockout blade 400 within a lockoutblade assembly 402 may be attached to one or both seat supporting crossmembers 364 and 366. When the user moves the lockout blade 400 to afirst position, the lockout blade assembly 402 locks the isolation stage300 in a position along the shaft 302, thereby preventing fore-aftmovement of the seat S relative to the active suspension system 20 c. Insome examples, the lockout blade 400 engages one of a plurality ofcorresponding slots (not shown) located along the shaft 302, which aresized and configured to receive the lockout 400 while in the firstposition. When the lockout blade 400 is moved to a second position, theblade disengages the corresponding slot in the shaft 302 and permits theisolation stage 300 to move in the fore-aft direction. In some examples,the lockout blade 400 is biased within the lockout blade assembly 402,by a spring or other means, toward the first and locked position. Whenthe blade 400 is moved to the second and unlocked position the user mustovercome the bias of the lockout blade assembly 402 toward the first andlocked position. In some examples, the blade assembly 402 includes adetent to control and regulate the movement of the lockout blade 400.

With renewed reference to FIG. 12, and in some exemplary embodiments, adamper assembly 410 can be included as part of isolation stage 300 whichallows the seat top to move with respect to the vehicle—for exampleperhaps when going over a speed bump which decelerates and thenaccelerates the vehicle causing a fore-aft disturbance. The driver isisolated from this disturbance because the seat is allowed to maintain amore constant forward speed while the vehicle changes speed due to thebump (decelerating at first and then accelerating). In general, theisolation stage comprises a bearing system which secures the seat top tothe mechanism but allows fore-aft motions. It also includes a set ofsprings which provide a centering force to keep the seat centerednominally so that it is ready to absorb motion when a disturbanceoccurs. The damper assembly 410 provides a mechanism to remove energyand to prevent or inhibit excessive or oscillatory motions. Damping canbe accomplished with a hydraulic damper, or in other ways as would beapparent to one skilled in the field.

Without a damper, the seat could oscillate for multiple cycles after adisturbance. The damper removes the energy and causes the motion todecay away more rapidly (i.e., return to center of travel smoothlywithout excessive overshoot or with unwanted oscillations). One end ofthe damper assembly may be coupled to the seat. The other end may becoupled to something “stationary”—i.e., on the vehicle side ofsystem—including components and or portions of the vehicle frame whichdo not move fore-aft with the seat as the seat moves relative to thevehicle. However, embodiments in which a damper is not included in asystem are also contemplated as the disclosure is not so limited.

As noted previously, the above described systems and methods may be usedto control movement of a seat relative to a vehicle to compensate formotion of the vehicle caused by road inputs, driver inputs, and/or othermulti-directional accelerations. However, as previously noted, in someembodiments, the use of two or more non-back-drivable actuators mayprovide various benefits. Accordingly, somewhat similar to the aboveembodiments, two non-back-drivable actuators may be connected toopposing sides or portions of a seat or seat bottom. Thesenon-back-drivable actuators may then be controlled cooperatively tocontrol both the “heave” motion of the seat along a vertical or Z-axisof the seat and the “roll” of the seat around an axis that is parallelto an X or longitudinal axis of the seat and/or vehicle. Specificembodiments of active suspension systems including non-back-drivableactuators that may be used to control motion of a vehicle seat aredetailed further below.

In one embodiment, a non-back-drivable actuator may correspond to arotational actuator including one or more worms that are rotated by andextend from the actuator. The worms may be engaged with a correspondingworm gear with appropriately sized and shaped teeth for engaging withthe worm. Rotation of the worm along one axis is transformed intorotational motion of the worm gear, and any component or structurerotatably fixed to the worm gear, into rotational motion about a secondaxis that may be approximately perpendicular to the axis of rotation ofthe worm. As detailed in regards to the figures, the worm gear may beoperatively connected with one or more portions of a transmission systemfor transforming motion of the worm into roll and/or heave of a seat.Depending on the particular embodiment, the worm gear may either be afull worm gear (e.g. it may extend over a full 360° to form a circle) orthe worm gear may only be a partial or sector worm gear that extendsover a range of angles that is less than 360° (e.g. the worm gear mayextend over an arc to form a semi-circular shape). Of course, it shouldbe understood that a worm gear may have any appropriate shape and/orrange of angular movement for engaging with a corresponding worm as thedisclosure is not limited in this fashion.

The ability of a worm drive (i.e. an actuator coupled to a worm andcorresponding worm gear) to resist being backdriven is related to anumber of different design considerations. Specifically, and withoutwishing to be bound by theory, the mechanical advantage of a worm driveis related to a pitch of the worm versus a radius of the associated wormgear. For example, larger pitches and smaller radii are associated lowermechanical advantage whereas smaller pitches and larger radii areassociated with larger mechanical advantages. Additionally, depending onthe particular embodiment, a motor of an actuator may either be directlyconnected to a worm and/or one or more intermediate transmissioncomponents such as gears and belts may be used which may be used toprovide a desired mechanical advantage between the motor and worm. Theresulting overall mechanical advantage of the actuator and friction ofthe worm drive may interact to resist the actuator being backdriven andmay provide a threshold force below which the actuator may not besubstantially backdriven. For example, larger mechanical advantages andincreased amounts of friction may be associated with increasedresistance of an actuator to resist being backdriven. In view of theabove, it should be understood that a non-back-drivable actuator may beappropriately designed using the above noted parameters to support theexpected dynamic and static loads during normal operation without ansubstantial amount of backdriven motion. Thus, the actuator may beconsidered to be effectively a non-back-drivable actuator.

While a particular type of non-back-drivable actuator is describedabove, it should be understood that the current disclosure is notlimited to the use of only non-back-drivable worm drives. For example,harmonic drives may be configured to be non-back-drivable. Additionally,ball screws with a sufficiently high mechanical advantage (i.e. ifcoupled to another gear reduction such as a belt drive or gear drive)may be considered to be non-back-drivable when coupled with motorfriction. Further, conventional lead screws (i.e a threaded rod in anut) can be non-back-drivable when designed with sufficient amounts ofmechanical advantage and friction. In view of the above, it should beunderstood that an effectively non-back-drivable actuator may beconsidered to be any actuator including a sufficient combination ofmechanical advantage and friction to support the expected static anddynamic forces during operation of a system without being substantiallyback driven even when the actuator is not being actively operated.Further, in some embodiments, it may be advantageous to provideincreased amounts of mechanical advantage in a non-back-drivableactuator to minimize the amount of friction present in a system toprovide the desired non-back-drivable characteristics of the actuator.

FIG. 14 depicts one embodiment of an active suspension system that maybe used to control motion of an associated vehicle seat usingnon-back-drivable actuators. As shown in the figure, the system includesa frame 91 which includes an opposing front and back portions as well asopposing side portions that extend between the front and back of theframe. Of course, while a square or rectangular frame is depicted in thefigures, it should be understood that any other appropriately shapedframe capable of supporting an active suspension system relative to anunderlying surface, such as an underlying vehicle interior surface, maybe used as the disclosure is not limited in this fashion.

In the depicted embodiment, the active suspension system may include afirst rocker arm 74 a and second rocker arm 84 a that extend between thefront and back opposing portions of the frame 91. The rocker armsinclude bars 102 and 112 that are rotatably connected to, and extendbetween, the opposing front and back portions of the frame. However,embodiments in which the bars are rotatably connected to differentportions of the frame, and/or are rotatably supported by otherstructures, are also contemplated. The bars may correspond to anyappropriate structure capable of transmitting a torque including, forexample, a hollow torque tube, a solid shaft, a solid portion of arocker arm through which a rotational axis passes, and/or any otherappropriate structure capable of transmitting torques. The rocker armsmay also include one or more portions, such as links 104, 106, 114, and116, that extend radially outward from an axis of rotation of the barsand rocker arms. Further, these links, or other radially extendingportions, may be rotatably fixed to the bars, or other portion of arocker arm, for transforming rotational motion of the bars and rockerarms into rotational and/or vertical motion of an associated portion ofvehicle seat, such as a seat base, connected thereto. For example, inthe depicted embodiment, the links associated with the rocker arms maybe rotatably fixed to two opposing portions, such as the two opposingends, of each of the rotatable bars.

As previously described, the links 104, 106, 114, and 116 may beconstructed to be connectable to an associated portion of a vehicleseat, such as opposing sides of a vehicle seat base. As also describedabove, in some embodiments, one or more of the links, such as links 114and 116 connected to the second rocker arm 84 a may be rotatablyconnected to pivoting links 118 and 120 respectively which areconnectable to the seat. These pivoting links may accommodate changes indistance between the links, rocker arms, and connected portions of aseat when the active suspension system is operated.

In the embodiment depicted in FIG. 14, the links 104 and 106 arerotatably fixed to a bar 102 of the first rocker arm and the links 114and 116 are rotatably fixed to the bar 112 of the second rocker arm 84a. The links associated with the opposing rocker arms may be orientedoutwards away from each other. Therefore, the portions of the rockerarms, i.e. the links, that are attached to an associated seat may belocated outwards relative to an axis of rotation of the associated barsand/or rocker arms the links are attached to. However, embodiments inwhich the links, or other radially extending portions of the rocker armsextend in the opposite direction, i.e. inwards towards each other, arealso contemplated as the disclosure is not so limited.

As also shown in FIG. 14, the depicted embodiment may also include afirst actuator 42 and second actuator 44. The actuators may be heldstationary relative to the frame 91 through either a direct or indirectconnection. However, as elaborated on further below, in some embodimentsone or more of the actuators may be displaceable relative to the framein one or more directions.

As previously noted, in some embodiments, one or both of actuators 42and 44 may be non-back-drivable actuators. For example, the firstactuator includes a first rotatable worm 500 that extends outwards fromthe first actuator. The first worm is engaged with corresponding teethformed on a first worm gear 504 that is rotatably fixed to a bar 102 ofthe first rocker arm 74 a. Similarly, the second actuator includes asecond rotatable worm 502 that extends outwards from the secondactuator. The second worm is also engaged with corresponding teethformed on a second worm gear 506 that is rotatably fixed to a bar 112 ofthe second rocker arm 84 a. In the depicted embodiment, the worm gearsare depicted as sector wheels that extend over a range of angles thatare less than 360°. However, embodiments in which the worm gears extendover 360° to form a full circle are also contemplated.

In the depicted embodiment, the worm gears 504 and 506 are rotatablyfixed to a portion of the associated bars 102 and 112 at a portionadjacent to, and/or integrated with, links 106 and 116 of the depictedrocker arms. Further, this location is depicted as being adjacent to anend of the depicted bars. However, embodiments in which the worm gearsare attached at different locations along a length of the bars, or otherrotatable portion of a rocker arm, are also contemplated. Additionally,while a direct connection between the worm gears and the bars of therocker arms has been depicted, in some embodiments, the worm gears maybe connected indirectly to the bars and/or any other appropriate portionof a rocker arm capable of applying a torque from the worm gears to theassociated rocker arm.

As noted previously, the above-noted worms and worm gears may beappropriately designed such that they are substantiallynon-back-drivable when subjected to the expected static and dynamicloads applied to the actuators during operation of the active suspensionsystem for controlling motion of a vehicle seat.

Having described the arrangement of the various components of the activesuspension system depicted in FIG. 14, operation of the activesuspension is now described in further detail below. Specifically, inthe various operating modes detailed below, the first actuator 42 andsecond actuator 44 are actuated to apply various combinations ofclockwise and counterclockwise torques and rotational displacements tothe corresponding worm gears they are engaged with which in turn appliesthese torques and rotational displacements to the associated firstrocker arm 74 a and second rocker arm 84 a.

In a first mode of operation, the first actuator 42 and second actuator44 may be actuated to rotate the first rocker arm 74 a and the secondrocker arm 84 a in the same direction. This will either roll an attachedvehicle seat in a first direction or a second opposing directiondepending on the particular direction the actuators rotate the rockerarms. For example, in reference to FIG. 14, the first and second rockerarms may both be rotated in a clockwise direction in the depictedembodiment. During such an operation, the portions of the links 104 and106 of the first rocker arm attached to an associated seat may bedisplaced vertically downwards from a first orientation to a secondlower orientation relative to an underlying surface of the vehicleinterior. Correspondingly, the portions of the links 114 and 116 of thesecond rocker arm attached to a seat, and/or the corresponding pivotlinks 118 and 120, are displaced vertically upwards from a firstorientation to a second higher orientation relative to the underlyingsurface of the vehicle interior. This will cause the sides of the seat,not depicted, to raise and lower correspondingly resulting in a roll ofthe seat. Rotation of the rocker arms in the opposite counterclockwisedirection will cause the seat to roll in the opposite direction.

In a second mode of operation, the first actuator 42 and second actuator44 may be actuated to rotate the first rocker arm 74 a and the secondrocker arm 84 a in opposite rotational directions. Depending on theparticular arrangement of the rocker arms and the directions of rotationapplied to the rocker arms by the actuators, an attached vehicle seatmay either be displaced vertically upwards away from, or verticallydownwards towards, an underlying surface of a vehicle interior. Forexample, in reference to FIG. 14, the first rocker arm may be rotated inthe counterclockwise direction and the second rocker arm may be rotatedin the clockwise direction. This may result in the portions of the links104, 106, 114, and 116 of the first and second rocker arms that areattached to an associated seat being displaced vertically upwards. Thisvertical upwards displacement of the links correspondingly displace anattached seat in the vertical upwards direction as well. Similarly, whenthe first and second rocker arms are displaced in the oppositedirections, the portions of the links attached to an associated vehicleseat may be displaced downwards which causes the vehicle seat to bedisplaced downwards as well.

In a third mode of operation, the first actuator 42 and second actuator44 may be actuated using a combination of the above noted modes ofoperation. Specifically, depending on the particular desired motion theactuators may be operated such that the portions of the rocker armsattached to an associated vehicle seat may move by different amountseither vertically upwards and/or downwards. This may create acombination of both roll and heave (i.e. rotation and verticaldisplacement relative to an underlying surface of the vehicle interior)that may be applied to the vehicle seat. For example, combinations ofroll and heave may be applied to a seat by rotating the first and secondrocker arms in the following ways: rotating the first and second rockerarms in the same direction with different rotational displacements;rotating the first and second rocker arms in opposite directions withdifferent amounts of rotational displacement; and/or rotating one of therocker arms while holding the other rocker arm stationary. Depending onthe particular arrangement of the rocker arms and specific appliedrotational displacements, this may move the attached vehicle seatvertically upwards or downwards while also applying either a positive ornegative rotation to the seat.

In the embodiment depicted in FIG. 14, the first and second actuators 42and 44 are disposed within an interior portion of the active suspensionsystem. The two worms 500 and 502 associated with the two actuatorsextend laterally outwards towards the sides of the active suspensionsystem's frame 91 where they are engaged with the corresponding wormgears 504 and 506. However, the current disclosure is not limited to thespecific arrangement of actuators, worms, worm gears, and rocker armsdepicted in this figure. Instead, the current disclosure encompasses anynumber of different arrangements of these features including theembodiments described below relative to FIGS. 15-18.

FIG. 15 depicts one embodiment of an active suspension system that mayinclude an increased stroke length for increased range of motion for anattached vehicle seat. In the depicted embodiment, the first and secondactuators 42 and 44 may be disposed adjacent to opposing exteriorportions of the active suspension system. The associated worms 500 and502 may extend from the associated actuators inwards towards thecorresponding worm gears 504 and 506 that they are engaged with.Correspondingly, this may permit the rocker arms 74 a and 84 a to haveaxes of rotation that are located closer to a vertically orientedmid-plane of the active suspension system relative to the vehicle'sframe of reference. By having the worm drives and axes rotation of therocker arms disposed between a vertical mid-plane of the activesuspension system and the corresponding actuators, it is possible to userocker arms radially extending portions, such as the above noted links,with longer lengths than those described above. These increased lengthsmay provide an increased radius of rotation for the rocker arms withcorrespondingly increased vertical displacements of a portion of a seatconnected to the rocker arms for similar amounts of rotationaldisplacement. In the depicted embodiment, the first and second actuatorsare depicted as being located in plane with one another. Howeverembodiments in which the first and second actuators are verticallyoffset from one another relative to an underlying surface of a vehicleinterior are also contemplated.

FIGS. 16 and 17 depict another embodiment of an active suspension systemthat may be used to control motion of a vehicle seat connected thereto.In the depicted embodiment, the active suspension system includes firstand second actuators 42 and 44. These actuators are disposed within aninterior portion of the active suspension system. The associated firstand second worms 500 and 502 of the first and second actuators extendlaterally outwards from the associated actuators towards opposing sidesof the active suspension system frame 91 where the worms are engagedwith corresponding first and second worm gears 504 and 506. In such anarrangement, the first and second rocker arms 74 a and 84 a, and theirassociated axes of rotation, may be located laterally outwards relativeto the first and second actuators.

As shown in FIG. 16, in some embodiments, the first and second actuators42 and 44 may be coaxial with one another such that the axis of rotationof the corresponding worms 500 and 502 may be aligned with one another.Further, in some embodiment, these coaxial actuators may includeopposing surfaces that are disposed against one another. Without wish tobe bound by theory, such an arrangement may help to mitigate opposingloads applied to the first and second actuators during operation.However, as shown in FIG. 17 embodiments in which the first and secondactuators are vertically offset from one another relative to anunderlying surface of a vehicle interior also contemplated. In such anembodiment, the worms 500 and 502 may either be oriented in the same ordifferent directions to engage with the corresponding worm gears 504 and506. Additionally, while not depicted in the figures, the first andsecond actuators may also be horizontally offset from one anotherrelative to the underlying surface of the vehicle interior as thedisclosure is not limited in this fashion.

FIG. 18 depicts an embodiment of an active suspension system where afirst actuator 42 may be used to control roll of a vehicle seat attachedto the suspension system and a second actuator 44 that may be used tocontrol heave of a vehicle seat attached to the suspension system. Thearrangement and operation of these actuators is detailed further below.

In the depicted embodiment, the first actuator 42 may be fixed in placerelative to a frame 91 of the active suspension system and/or anunderlying surface of the vehicle interior. The first actuator 42includes a first worm 500 that extends outwards from the first actuatorand is engaged with a threaded portion of a support 508. The support 508may be free to move in an axial direction in response to rotation of thefirst worm. For example, the first worm may be engaged with the threadedportion of the support while the first actuator is prevented from movingaxially. The support 508 may be fixed to a second actuator 44. The firstactuator may be rotatably fixed relative to the support through the useof any appropriate arrangement including for example rails, pin andgroove arrangements, and/or any other appropriate support structurecapable of preventing rotational motion of the first actuator relativeto the support while permitting axial movement of the support andconnected second actuator. Thus, when the first worm is rotated, thesupport and second actuator may be moved in either a first axialdirection and/or an opposing second axial direction depending on thedirection of rotation of the first worm of the first actuator.

As also shown in the figure, the second actuator 44 may include twoworms, i.e. second and third worms 502 a and 502 b, that extend outwardsfrom two opposing sides of the second actuator in opposite directions.The second worm may be engaged with a first worm gear 504 that may berotatably fixed to a first rocker arm 74 a as previously describedabove. Similarly, the third worm may be engaged with a second worm gear506 that is rotatably fixed to a second rocker arm 84 a. In someembodiments, the second and third worms may be formed on a single shaftthat extends through the second actuator, and the second and third wormsmay have threads that are oriented in opposing directions. For example,one worm may have a left-handed (LH) thread and the other worm may havea right-handed (RH) thread. Correspondingly, when the second actuator isactuated, the second and third worms may rotate in the same directionwhile rotating the first and second worm gears, as well as theassociated rocker arms, in opposite directions relative to one another.As described above, rotation of the rocker arms in opposing directionsmoves the radially extending portions of the rocker arms connected to anassociated vehicle seat either vertically up or down relative to anunderlying surface of the vehicle interior. Thus, actuation of thesecond actuator may be used to control heave of a connected vehicleseat.

In some embodiments, the first actuator 42 may be disposed on and/or maybe axially fixed to the second actuator 44. The first actuator may beaxially fixed to the second actuator using any appropriate connectionincluding both direct and indirect connections. In either case, when thefirst actuator is actuated to axially displace the first actuator in anaxial direction due to rotation of the associated first worm 500, thesecond actuator may also be axially displaced in the same axialdirection. This axial movement of the second actuator results in acorresponding axial movement of the associated second and third worms502 a and 502 b in the same direction which produces a correspondingrotation of the associated first and second worm gears 504 and 506. Dueto the arrangement of the worm gears and associated worms, the wormgears rotate in the same direction. Therefore, when the first actuatoris actuated to rotate the first worm in a first direction, the wormgears and associated rocker arms are rotated in a first rotationaldirection. Correspondingly, when the first actuator is actuated torotate the first worm in a second opposite direction, the worm gears andassociated rocker arms are rotated in a second opposing rotationaldirection. As described previously rotation of the rocker arms inopposing directions from one another may be used to control roll of avehicle seat attached to the rocker arms. Thus, actuation of the firstactuator may be used to control roll of the attached vehicle seat.

In view of the above, the first and second actuators 42 and 44 may beoperated cooperatively to control both a roll and heave of a vehicleseat attached to the depicted active suspension system. Without wishingto be bound by theory, the depicted arrangement of the first and secondactuators may provide several benefits. For example, due to the secondactuator supporting the loads associated with controlling heave of theassociated vehicle seat, reduced axial loads may be applied to a frameand/or underlying portion of the vehicle interior in such an embodiment.Additionally, such an arrangement may provide a more compact mechanismthat occupies less of the limited space available beneath typicalvehicle seats.

In the above described embodiments, it should be understood that theactuators and associated components engaged with the rocker arms, suchas the above described worms and worm gears, may be located in anyappropriate portion of an active suspension system and may be orientedin any appropriate direction. However, in one embodiment, the actuatorsand associated moving components may be disposed within a front portionof the active suspension system that is located adjacent to a frontportion of an attached vehicle seat. This may place the actuators andmoving components further away from an opposing rear portion of theactive suspension system that is located adjacent to a rear of the seat.Such an arrangement may help to physically isolate the moving componentsof the active suspension system to avoid unintentional damage orobstruction of the components while also providing additional open spaceunder the seat for rear seat occupants.

As previously discussed, in some embodiments, it may be desirable toinclude one or more components in an active suspension system that helpto partially bear the weight of a vehicle seat and its occupant. Withoutwishing to be bound by theory, by offsetting the weight of the passengerand seat, the friction levels in the active suspension system may bereduced and the amount of power required to operate the system may bereduced without compromising performance.

FIGS. 19-20 show one embodiment of an active suspension system that isconstructed to at least partially support the weight of a vehicle seatand its occupant without operation of the associated actuators.Specifically, as detailed further below, one or more torsion springs maybe incorporated into a system to at least partially support the weightof a vehicle seat and its occupant.

In the depicted embodiment, an active suspension system may have asimilar arrangement to those described above. Specifically, first andsecond actuators 42 and 44 may be operatively coupled to rotatable firstand second bars 102 and 112 of first and second rocker arms 74 a and 84a. In some embodiments, the depicted actuators may be non-back-drivableactuators. However, embodiments in which back-drivable actuators areused are also contemplated.

To help bear the loads applied to the first and second rocker arms 74 aand 84 a, a first torsion spring 510 may be operatively coupled to thefirst bar 102 of the first rocker arm to apply a torque to the firstbar. Similarly, a second torsion spring 512 may be operatively coupledto the second rocker arm to apply a torque to the second bar. Thetorsion springs may be constructed and arranged such that the torquesthey apply to the associated bars of the rocker arms are orientedsupport a weight of the vehicle seat and occupant. In some instancesthese torques applied to the bars of the rocker arms may be consideredto be applied in parallel to the torques applied to the first and secondrocker arms by the associated first and second actuators. Thus, thetorsion springs may apply a secondary torque to the bars, or otherportion, of the rocker arms that is separate from the torques applied bythe associated actuators to support at least a portion of the loadsapplied during operation.

The figures show one possible embodiment in which one or more torsionsprings may be integrated with an active suspension system. As shown inthe figures, the first and second rotatable bars 102 and 112 of thefirst and second rocker arms 74 a and 84 a may include internal cavities518 and 520 that pass at least partially, and in some instancescompletely, through the associated bars. In the depicted embodiment, thefirst and second torsion springs 510 and 512 are torsion spring barsthat are disposed at least partially in, and may extend out of, thecorresponding cavities of the bars they are associated with. In someembodiments, the torsion springs may be coaxially arranged with theassociated bars. The first and second torsion springs may be rotatablyfixed relative to the first and second bars of the rocker armsrespectively. For example, an end portion of the first torsion springmay be rotatably fixed to the first bar at a first connection 512located within the first cavity. Similarly, an end portion of the secondtorsion spring may be rotatably fixed to the second bar at a secondconnection 514 located within the second cavity. Appropriate types ofconnections may include, but are not limited to welds, pins, threadedfasteners, brazed joints, adhesives, mechanically interlocking features,and/or any other appropriate form of connection capable of rotatablyfixing the torsion springs to an associated bar or other rotatablecomponent of a rocker arm.

To apply the desired torques to the associated rocker arms, the activesuspension systems may include supports 522 that may support an end ofan associated torsion spring. For example, as shown in the figures, thetorsion springs 510 and 514 may include end portions, which are depictedas a bent end on the torsion spring bars, that are rotatably fixed inplace relative to a frame 91 of the active suspension system by thesupports. Specifically, as shown in the figures, the supports maycorrespond to any appropriate feature that is capable of engaging withand preventing rotation of an attached portion of a torsion springincluding, for example, protrusions that prevent rotation, mechanicallyinterlocking features, fasteners, welds, interference fits, and/or anyother appropriate structure. Further, in some embodiments, the torsionsprings may be integrated with the rocker arms and/or frame of theactive suspension system such that the torsion springs do not obstructan opening in the rear of a connected vehicle seat.

During operation, the first and second actuators 42 and 44 may beoperated to apply a first torque to the associated first and secondrocker arms 74 a and 84 a respectively to move the first and secondrocker arms to desired orientations. The above noted first and secondtorsion springs 510 and 514 may apply a corresponding second torque toeach of the rocker arms that is applied in parallel to the torquesapplied by the associated actuators. These secondary torques may beapplied during both static and dynamic operation and may be viewed as atleast partially, and in some embodiments completely, supporting at leastthe static loads, and at least a portion of the dynamic loads, appliedto the rocker arms during operation. Thus, the use of the torsionsprings may enable the actuators to operate at reduced torque levelsduring both active and static operation, reduce friction on startup, andreduce overall power consumption.

In some embodiments, it may be desirable to vary a torque applied to arocker arm by an associated torsion spring. For example, a torque may bevaried to support different loads applied to a vehicle seatcorresponding to passengers, and/or other loads, supported on the seatwhich may have different weights. Similar to the embodiments describedabove, FIG. 20 depicts an active suspension system including first andsecond rocker arms 74 a and 84 a along with corresponding first andsecond torsion springs 510 and 514. However, unlike the static supportsdescribed above, an end portion of one or more of the torsion springsmay be supported by a movable support such as an output shaft of one ormore linear actuators 524 and 526. Specifically, the linear actuatorsmay be operated to displace an end of the associated torsion springwhich causes the torsion spring to twist about its axis of rotation.Depending on the direction of the actuation, this may either result inan increased or decreased amount of torque applied to a rocker arm bythe associated torsion spring.

While the use of linear actuators to displace the ends of torque bars tovary an applied torque has been shown in the figures, the currentdisclosure is not limited to only the depicted embodiment. For examplein another embodiment a helical torsion spring may include an endportion that is connected to a rotatable drive shaft which may be drivenby an associated rotational actuator to vary an amount of torqueprovided by the torsion spring. In either case, it should be understoodthat any appropriate type of actuator and/or method that may be used tovary the torque applied by a torsion spring to an associated rocker armmay be used as the disclosure is not limited in this fashion.

The above noted embodiments depict a system that includes torsion springbars that are coaxially disposed within interior cavities of associatedrotatable bars. However, other embodiments with different types andarrangements of torsion springs are contemplated. For example, torsionsprings may be: offset from the rotation axis of an associated bar orrocker arm; disposed around an exterior of the associated bar or rockerarm; disposed adjacent to an associated bar or rocker arm, and/orremoved from an associated rotatable bar or rocker arm. Additionally,the disclosed torsion springs may be indirectly coupled as thedisclosure is not limited to only direct couplings with torsion springs.It should also be understood that any appropriate type of torsion springmay be used to apply the desired torques. For example appropriate typesof torsion springs may include, but are not limited to, solid torsionspring bars, torsion spring tubes, helical torsion springs, and/or anyother appropriate type of torsion spring.

While the present teachings have been described in conjunction withvarious embodiments and examples, it is not intended that the presentteachings be limited to such embodiments or examples. On the contrary,the present teachings encompass various alternatives, modifications, andequivalents, as will be appreciated by those of skill in the art.Accordingly, the foregoing description and drawings are by way ofexample only.

What is claimed is:
 1. An active suspension system configured to supporta vehicle seat relative to a floor of a vehicle, the active suspensionsystem comprising: a first actuator of the active suspension system; afirst rocker arm operatively connected to the first actuator, whereinthe first rocker arm is operatively coupled to the vehicle seat suchthat rotation of the first rocker arm induces motion of the vehicle seatrelative to the floor of the vehicle, wherein the first actuator isconstructed to apply a torque to the first rocker arm; and a firsttorsion spring, wherein the first torsion spring applies a torque to thefirst rocker arm.
 2. The active suspension system of claim 1, furthercomprising a second actuator, a second rocker arm, and a second torsionspring, wherein the second rocker arm is operatively connected to thesecond actuator, wherein the second rocker arm is constructed to beconnected to the vehicle seat, wherein the second actuator isconstructed to apply a torque to the second rocker arm, and wherein thesecond torsion spring applies a torque to the second rocker arm.
 3. Theactive suspension system of claim 1, wherein the first torsion spring isa first torsion bar spring.
 4. The active suspension system of claim 1,wherein the torque applied to the first rocker arm by the first torsionspring is variable.
 5. The active suspension system of claim 1, whereinthe first actuator is a non-back-drivable actuator.
 6. The activesuspension system of claim 2, wherein the second actuator is anon-back-drivable actuator.
 7. The active suspension system of claim 2,wherein the second torsion spring is a second torsion bar spring.
 8. Theactive suspension system of claim 7, wherein the first torsion springand the second torsion bar spring are configured to move independentlyand relative to one another.
 9. A method of operating an activesuspension system to support a vehicle seat relative to a floor of avehicle, the method comprising: applying a first torque to a firstrocker arm connected to the vehicle seat with a first actuator; andapplying a second torque to the first rocker arm in parallel with thefirst torque.
 10. The method of claim 9, further comprising applying athird torque to a second rocker arm connected to the vehicle seat with asecond actuator, and applying a fourth torque to the second rocker armin parallel with the third torque.
 11. The method of claim 9, whereinthe second torque is applied with a torsion spring.
 12. The method ofclaim 9, further comprising varying the second torque.
 13. The method ofclaim 9, wherein the first actuator is a non-back-drivable actuator.